Clade Mammaliaformes Rowe 1988 [Rowe 1988]
   [crown] Class Mammalia Linnaeus, 1758 - mammals
     Subclass Theriiformes (Rowe, 1988) M.C. McKenna & S.K. Bell, 1997 see Division Theriiformes
       Infraclass Holotheria (Wible et al., 1995) M.C. McKenna & S.K. Bell, 1997 see [unranked] Holotheria
         Superlegion Trechnotheria McKenna, 1975 see [unranked] Trechnotheria McKenna, 1975
           Legion Cladotheria McKenna, 1975 see [unranked] Cladotheria McKenna, 1975
             Sublegion Zatheria McKenna, 1975 see [unranked] Zatheria McKenna, 1975
               Infralegion Tribosphenida McKenna, 1975 see Sublegion Boreosphenida
                 Supercohort Theria (Parker & Haswell, 1897) M.C. McKenna & S.K. Bell, 1997 - therians see [unranked] Theria
                   Cohort Marsupialia - marsupials
                     Magnorder Ameridelphia (Szalay, 1982) M.C. McKenna & S.K. Bell, 1997
                       Order Didelphimorphia Gill, 1872
                         Family Didelphidae Gray, 1821 - American opossums
                           Subfamily Didelphinae (Gray, 1821) Simpson, 1927
                             Tribe Monodelphini (Talice et al., 1960) M.C. McKenna & S.K. Bell, 1997
                               Subtribe †Zygolestina (Marshall, in Archer, ed., 1987) M.C. McKenna & S.K. Bell, 1997
                                 Genus †Zygolestes Ameghino, 1898